Oat-based products with high oat protein content and functionality and production processes thereof

ABSTRACT

The present disclosure provides a novel and gentle process for producing oat-based products containing oat proteins that have good functional properties, including solubility, emulsifying, foaming and gelling properties. This process includes hydrolysis to break down carbohydrates, physical separation to remove insoluble fibers, and membrane filtration to concentrate oat proteins by the removal of sugars. The method can include providing an oat mixture; hydrolyzing the oat mixture with an enzyme or a combination of enzymes; physically separating an insoluble material from the hydrolyzed oat mixture to form a soluble hydrolyzed oat mixture; applying membrane filtration to the soluble hydrolyzed oat mixture using a membrane having molecular weight cut-offs (MWCO) greater than 100 kDa.

BACKGROUND

Due to concerns of, for example, allergies, lactose intolerance,calories, and cholesterol, many consumers need or prefer dairyalternatives/replacement food/drink products. In recent years, plantproteins have received a lot of attention as alternative protein sourcesin food/drink formulations due to their sustainability, low productioncost, and health benefits. Protein food/drink products using plantsources, such as soy, pea, oat, rice, coconut, almond, cashew and hemp,are commercially available.

Oats are well received by consumers who have or prefer a healthylifestyle and have been consumed in many different forms, such as rolledoats, bread, biscuits, cookies, cereals, etc. Oats have a very pleasantand round taste as well as much better sensorial attributes compared tomany other plant protein sources.

However, limitations such as low availability and poor functionalityhave hindered wide applications of oat proteins. Commercial oat-basedbeverages usually contain very low amounts of oat proteins (from 0 to1%), which makes them poor options as dairy alternatives. The lowprotein content in commercial oat-based beverages is mainly becausethese beverages are usually produced from oat flours, which have a lowprotein content (<13%). To increase the protein content, a high amountof oat flours can be used for production, but this would result instability issues of the produced beverages.

Commercially available oat protein concentrates containing high oatprotein contents can also be used to produce oat-based beverages.However, these commercial oat protein concentrates can have a very poorstability in water, and thus their applicability for liquid andsemi-solid products are limited. This is mainly because the existingprocesses used to isolate the oat protein from the raw material impactthe oat protein structure, thereby drastically reducing proteinsolubility and other functional properties (e.g., emulsifying, foamingand gelling properties) of the oat protein.

Thus, the final products using these commercial oat protein concentratescan have sandy mouthfeel and sedimentation, which are not preferred byconsumers.

SUMMARY

The present disclosure provides a novel and gentle process for producingoat-based products containing oat proteins that have good functionalproperties, including solubility, emulsifying, foaming and gellingproperties. This process includes hydrolysis to break downcarbohydrates, physical separation to remove insoluble fibers, andmembrane filtration to concentrate oat proteins by the removal ofsugars.

In an embodiment, a method for producing an oat-based product comprisesproviding an oat mixture, preferably having a total solids (TS) of10-25%; hydrolyzing the oat mixture with an enzyme or a combination ofenzymes, preferably at a temperature between 60° C. and 70° C., morepreferably at 60° C.; physically separating an insoluble material fromthe hydrolyzed oat mixture by decantation and/or sieving to form asoluble hydrolyzed oat mixture; applying membrane filtration, preferablyat a temperature from 50° C. to 60° C., to the soluble hydrolyzed oatmixture using a membrane having molecular weight cut-offs (MWCO) greaterthan 100 kDa, preferably greater than or equal to 500 kDa, to obtain aretentate.

In a particular preferred embodiment the membrane filtration is applied,preferably at a temperature from 50° C. to 60° C., to the solublehydrolyzed oat mixture at TS from about 10% to about 15%, preferablyabout 10%. More preferably this membrane filtration is using a membranehaving molecular weight cut-offs (MWCO) greater than 100 kDa, preferablygreater than or equal to 500 kDa, to obtain a retentate.

In an embodiment, the hydrolyzed oat mixture is homogenized after thehydrolysis of the oat mixture, preferably at 60° C. and 200/50 bars.

In an embodiment, physically separated insoluble fibers are freeze-driedor spray dried.

In an embodiment, a permeate is obtained from the membrane filtrationand steamed and/or evaporated,

In an embodiment to produce an oat-based ready-to-drink (RTD) product,at least one of sugar, preferably sucrose; the evaporated permeate; oil,preferably sunflower oil; buffer salts and sources of calcium,preferably dipotassium phosphate and tricalcium phosphate; or flavorenhancers, preferably sodium chloride is added to the retentate to forma mixture. Additionally, an ultra-high temperature (UHT) treatmentincluding up or downstream homogenization can also be applied to themixture; and the heat-treated mixture is then aseptically packaged.

In an embodiment, the oat mixture comprises an oat raw material selectedfrom the group consisting of oat flour, defatted oat flour, oat flakes,and mixtures thereof; preferably defatted oat flour.

In an embodiment, the enzyme comprises at least one of amylase,amyloglucosidase, or β-glucanase; preferably amylase(s); or amylase andβ-glucanase; or α-amylase and amyloglucosidase; or amylase, β-glucanase,and amyloglucosidase. In an embodiment, a total amount of the enzymeused for hydrolyzing the oat mixture is from 0.05 wt % to 0.3 wt %,preferably 0.2 wt %, of the oat raw material.

In an embodiment, the enzyme is inactivated at 90° C. to 95° C. for10-15 minutes, and the hydrolyzed oat mixture is cooled to 20-60° C.,preferably 60° C., after the inactivation of the enzyme.

In an embodiment, the membrane comprises a hydrophilic, hydrophobic, oran inorganic membrane, more preferably a ceramic membrane.

In an embodiment, an oat protein concentrate produced by the presentprocess comprises 5-10 wt % of oat proteins; 2-7 wt % of fat; 5-20 wt %of carbohydrates; 2-4 wt % of sugars, mostly maltose; and 1-2 wt % oftotal dietary fibers comprising (i) 1-1.5 wt % of insoluble fibers and(ii) up to 0.5 wt % of soluble fibers comprising β-glucans, wherein theoat protein concentrate has a TS of 20-30%.

In an embodiment, the oat proteins in the oat protein concentrate has asolubility of 20% at pH 4 and of 83-86% from pH 7 to pH 11.

In an embodiment, the present disclosure provides an oat-based ready-todrink (RTD) beverage comprising the oat protein concentrate; andoptionally at least one of sugar, preferably sucrose; the evaporatedpermeate; oil, preferably sunflower oil; buffer salts and sources ofcalcium, preferably dipotassium phosphate and tricalcium phosphate; orflavor enhancers, preferably sodium chloride.

In an embodiment, the oat RTD beverage comprises at least 3 wt %,preferably 3 to 5 wt % of oat proteins and/or 3-5 g oat proteins/100 mlof the oat RTD beverage; 3-5 g sugars/100 ml of the oat RTD beverage;and 1.5-3 g fat/100 ml of the oat RTD beverage. The oat RTD beverage canhave a viscosity of 15-40 mPa·s (25° C., 100 s⁻¹).

In an embodiment, an oat syrup prepared from the permeate of the presentprocess comprises up to 1 wt % of oat proteins; up to 0.1 wt % of fat;40-50 wt % of carbohydrates; 20-30 wt % of sugars, mostly maltose; andup to 0.5 wt % of fibers. The oat syrup can have a TS of 65-80%.

In an embodiment, a natural fiber product prepared by the presentprocess may have a composition of (i) 4-10 wt % of oat proteins; 1-4 wt% of fat; 5-20 wt % of carbohydrates; 2-3 wt % of sugars, mostlymaltose; and 5-20 wt % of total dietary fibers comprising about 0.1-1 wt% of soluble fibers (beta-glucan), wherein the natural fiber product hasa TS of 15-50%; and/or (ii) 15-30 wt % of oat proteins; 3-10 wt % offat; 20-40 wt % of carbohydrates; 4-16 wt % of sugars; and 16-60 wt % oftotal dietary fibers comprising 15-56 wt % of insoluble fibers and 1-4wt % of soluble fibers, wherein the natural fiber product has a TS of90-98%.

An advantage of the present disclosure is to provide a method forproducing oat-based products that contain highly functional oat proteinswith high stability, solubility, gelation, emulsification, and foamingproperties.

Another advantage of the present disclosure is to provide a method forproducing oat-based products that have smooth taste and mouthfeel.

Yet another advantage of the present disclosure is to provide a methodfor producing oat-based products that have a high oat protein content.

An additional advantage of the present disclosure is to provide a methodfor producing oat-based products that have a controlled sugar content;i.e., sugar generation by modulation of the enzymatic hydrolysis stepand/or sugar removal by modulation of the membrane filtration step.

Another advantage of the present disclosure is to provide a method forproducing oat-based products that have a modulated protein/sugar ratio.

Still another advantage of the present disclosure is to provide dairyalternative protein products that contain highly functional proteinswith high stability, solubility, gelation, emulsification, and foaming.

Another advantage of the present disclosure is to provide dairyalternative protein products that have smooth taste and mouthfeel.

Yet another advantage of the present disclosure is to provide dairyalternative protein products that have a high protein content.

An additional advantage of the present disclosure is to provide dairyalternative protein products that have a modulated protein/sugar ratio.

Additional features and advantages are described herein, and will beapparent from, the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the protein solubility profile of the oat proteinconcentrate produced by the present process as a function of pH comparedto a commercial oat protein concentrate.

FIG. 2 shows the foaming volume profile of the oat protein concentrateproduced by the present process as a function of time compared to acommercial oat protein concentrate.

FIG. 3 shows the RVA profiles of oat flour in water (TS=15%) duringhydrolysis with different enzymes.

FIG. 4 shows a zoom-in of the RVA profiles of oat flour in water(TS=15%) during hydrolysis with different enzymes shown in FIG. 3 .

FIG. 5 shows the flux during flat sheet membrane filtration of samplesproduced with different TS values where BAN™480 L was used either aloneor in combination with Termamyl®. All samples were treated with 0.2 wt %enzyme(s) per weight of oat flour. BAN480L and Termamyl® were combinedin a 1:1 ratio.

FIG. 6 shows the permeate flux during flat sheet membrane filtration(MWCO=500 kDa) of different hydrolyzed oat mixtures made using adecanter at different initial TS values.

DETAILED DESCRIPTION

The various aspects and embodiments according to the present disclosure,as set forth herein, are illustrative of the specific ways to make anduse the invention and do not limit the scope of invention when takeninto consideration with the claims and the detailed description. It willalso be appreciated that features from aspects and embodiments of theinvention may be combined with further features from the same ordifferent aspects and embodiments of the invention.

As used in this detailed description and the appended claims, thesingular forms “a,” “an” and “the” include plural referents unless thecontext clearly dictates otherwise. For example, reference to “aningredient” or “a method” includes a plurality of such “ingredients” or“methods.” The term “and/or” used in the context of “X and/or Y” shouldbe interpreted as “X,” or “Y,” or “X and Y.” Similarly, “at least one ofX or Y” should be interpreted as “X,” or “Y,” or “both X and Y.”Similarly, the words “comprise,” “comprises,” and “comprising” are to beinterpreted inclusively rather than exclusively. Likewise, the terms“include,” “including” and “or” should all be construed to be inclusive,unless such a construction is clearly prohibited from the context.However, the embodiments provided by the present disclosure may lack anyelement that is not specifically disclosed herein. Thus, a disclosure ofan embodiment defined using the term “comprising” is also a disclosureof embodiments “consisting essentially of” and “consisting of” thedisclosed components. “Consisting essentially of” means that theembodiment or component thereof comprises more than 50 wt. % of theindividually identified components, preferably at least 75 wt. % of theindividually identified components, more preferably at least 85 wt. % ofthe individually identified components, most preferably at least 95 wt.% of the individually identified components, for example at least 99 wt.% of the individually identified components.

All ranges described are intended to include all numbers, whole orfractions, contained within the said range. As used herein, “about,”“approximately” and “substantially” are understood to refer to numbersin a range of numerals, for example the range of −10% to +10% of thereferenced number, preferably −5% to +5% of the referenced number, morepreferably −1% to +1% of the referenced number, most preferably −0.1% to+0.1% of the referenced number. Moreover, these numerical ranges shouldbe construed as providing support for a claim directed to any number orsubset of numbers in that range. For example, a disclosure of from 1 to10 should be construed as supporting a range of from 1 to 8, from 3 to7, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, and so forth. As usedherein, wt. % refers to the weight of a particular component relative tototal weight of the referenced composition. Material that passes througha membrane is called “permeate”; material that does not pass through amembrane and is recirculated is called “retentate”.

In the context of the invention, the term “oat-based products” refers tothe products which comprise oat proteins and which are obtained by theprocess of the invention. Depending on the final step, it refers to theretentate (final step=membrane filtration) or to ingredients/foodproducts, e.g. oat-based RTD beverage, derived from the furtherprocessing of the retentate obtained after membrane filtration.Additionally, it may also refer to the products which comprise oatfibers and/or carbohydrates and which are obtained by the process of theinvention. In particular, it may refer to the permeate which is obtainedafter the membrane filtration step and which may be optionally steamedand/or evaporated after the membrane filtration step. Alternately, itmay refer to the physically separated insoluble fibers which areobtained after decantation and/or sieving and which may be optionallyfreeze dried or spray dried after decantation and/or sieving. In apreferred embodiment, the term “oat-based products” refers to theretentate or to the oat-based RTD beverage. More preferably, it refersto the retentate.

All percentages expressed herein are by weight of the total weight ofthe composition unless expressed otherwise. When reference is made tothe pH, values correspond to pH measured at 25° C. with standardequipment.

“Astringency” is generally recognized as a feeling of puckering anddryness in the palate and is known to build in intensity and becomeincreasingly difficult to clear from the mouth over repeated exposures.Astringency is a dry sensation experienced in the mouth and is commonlyexplained as arising from the loss of lubricity owing to theprecipitation of proteins from the salivary film that coats andlubricates the oral cavity. Astringency is not confined to a particularregion of the mouth but is a diffuse surface phenomenon, characterizedby a loss of lubrication, which takes a time of the order of 15-20seconds to develop fully. Therefore, astringency is quite different fromthe more well-known taste sensations.

A “ready to drink” beverage or “RTD” beverage is a beverage in liquidform that can be consumed without further addition of liquid. Preferablyan RTD beverage is aseptic.

A “liquid concentrate” or “concentrate” is a liquid that is formulatedto be diluted before administration. Further in this regard, the liquidconcentrates disclosed herein are only administered after addition ofanother ingredient, such as a liquid diluent.

The present disclosure provides a novel and gentle process for producingoat-based products containing proteins that have good solubility as wellas other functional properties. This process includes hydrolysis tobreak down carbohydrates, physical separation to remove insolublefibers, and membrane filtration to concentrate oat proteins by theremoval of sugars.

In a general embodiment, the present disclosure provides a process ofproducing an oat-based product. The process comprises hydrolyzing an oatmixture with an enzyme, physically separating an insoluble material fromthe hydrolyzed oat mixture by decantation and/or sieving to form asoluble hydrolyzed oat mixture, and applying membrane filtration to thesoluble hydrolyzed oat mixture using a membrane having molecular weightcut-offs (MWCO) greater than 100 kDa, preferably greater than or equalto 500 kDa, to obtain a retentate.

The oat mixture may comprise an oat raw material, such as oat flour,defatted oat flour, oat flakes, or mixtures thereof. In one embodiment,the oat flour used may contain about 10-15 wt % proteins, about 4-6 wt %fat, about 55-70 wt % carbohydrates, and about 8-11 wt % fibers. The oatflour can have a TS of about 90-95 wt %. The oat mixture preferablycomprises defatted oat flour, which can lead to a high oat proteinrecovery yield over the process. For example, the defatted oat flour maycontain less than about 4 wt % fat, preferably less than about 3 wt %fat.

The oat raw material may be initially mixed with water to prepare theoat mixture. The oat mixture may have a total solids (TS) of 10≤TS≤25%before the subsequent membrane filtration, preferably 10≤TS≤15%. Forexample, the oat mixture can have a TS of about 10%, 15%, 20%, or 25%.The mixture can be diluted to have a desirable TS before the membranefiltration. The oat mixture preferably has a TS from about 10% to about15% before the membrane filtration, for example, about 10% or about 15%,preferably about 10%.

The oat mixture can then be hydrolyzed by an enzyme or an enzyme mixtureat a suitable temperature, for example, between about 60° C. and about70° C., preferably at about 60° C. At the suitable temperature, thestarch in the oat mixture starts the process of gelatinization. Thetemperature of this step is chosen based on the optimal temperatures forthe activity of the enzyme(s) being used.

The enzymatic hydrolysis step can be performed for a suitable period oftime depending on factors such as the enzyme(s) used, enzymeconcentration, and/or the conditions of the hydrolysis (time,temperature). In some embodiments, the enzymatic hydrolysis step can beperformed for about 30 minutes or 2 hours, preferably for 1 hour. Inanother preferred embodiment, the enzymatic hydrolysis step is performedfor 30 minutes to 2 hours, more preferably for 45 minutes to 90 minutes,most preferably for 45 minutes to 75 minutes.

The enzyme can comprise at least one of amylase, amyloglucosidase, orβ-glucanase. The enzyme may comprise amylase; a mixture of amylase andβ-glucanase; a mixture of α-amylase and amyloglucosidase; or a mixtureof amylase, β-glucanase, and amyloglucosidase. Combinations of enzymescan lead to a higher oat protein recovery yields over the processcompared to when amylase is used alone. Enzymatic hydrolysis withβ-glucanase activity is needed to reduce viscosity and to avoid blockingthe filtration membrane. This activity may be found through a specificenzyme or through a side activity of amylases. Hence, in a preferredembodiment, the enzyme comprises β-glucanase and/or amylase withβ-glucanase side activity. When the enzyme does not compriseβ-glucanase, it comprises amylase with β-glucanase side activity. Inparticular, the enzyme may comprise amylase with β-glucanase sideactivity; a mixture of amylase and β-glucanase; a mixture of α-amylasewith β-glucanase side activity and amyloglucosidase; or a mixture ofamylase, β-glucanase, and amyloglucosidase. It may also comprise amixture of amylase with β-glucanase side activity and β-glucanase or amixture of amylase with β-glucanase side activity, β-glucanase, andamyloglucosidase.

In a preferred embodiment, the enzyme is free from protease or enzymeswith protease side activity. Indeed, it is advantageous that the oatproteins remain intact and are not broken down into peptides. Inparticular, the oat proteins should remain intact to be collected andconcentrated in the retentate. If they are broken down into peptides,peptides would pass through the membrane during the membrane filtrationstep and would be collected in the permeate which also comprisesundesirable compounds (e.g. carbohydrates). Moreover, without wishing tobe bound by theory, the hydrolysis of oat proteins by protease wouldgenerate an undesirable bitterness which would be unpleasant, inparticular for food applications. A total amount of the enzyme used forhydrolyzing the oat mixture can be from about 0.05 wt % to about 0.3 wt%, for example, from about 0.05 wt % to about 0.2 wt %, from about 0.1wt % to about 0.3 wt %, from about 0.1 wt % to about 0.2 wt %, fromabout 0.15 wt % to about 0.25 wt %,

preferably about 0.2 wt %, of the oat raw material. Preferably, a totalamount of about 0.2 wt % enzyme of the oat raw material is used for thehydrolysis. Lower dosages of enzymes may lead to lower oat proteinrecovery yields.

The enzyme(s) are added to hydrolyze the carbohydrate fraction, such asstarch and/or fiber of the oat raw material. In particular, theenzyme(s) hydrolyze soluble fibers mainly into mono- or disaccharides(e.g. maltose). This step reduces the viscosity of the oat mixture tofacilitate its processability and to avoid fouling during the membranefiltration step.

Optionally, a homogenization step can be applied to break down largeparticles present in the oat mixture after the hydrolysis step. Thehomogenization step can be applied at 60° C. This step can lead to anincrease in the oat protein recovery yield compared to a process wherethis step was not performed.

The homogenization step can be applied at a temperature, for example,from about 40° C. to about 80° C., preferably from about 50° C. to about70° C., more preferably from about 55° C. to about 65° C., and mostpreferably at about 60° C. The homogenization step is preferably appliedat 200/50 bars.

An enzyme inactivation step can then be applied in order to stop theenzyme(s) activity. Otherwise, the enzyme(s) may remain active in thefinal product, which may lead to food quality issues. The enzymeinactivation step can be applied at a temperature from about 90 to about95° C. This step can be applied for a time period of about 10-15minutes.

The hydrolyzed oat mixture can be cooled to about 20-60° C. after theinactivation of the enzyme. Preferably, the hydrolyzed oat mixture iscooled to a temperature of 60° C.

High amounts of insoluble fiber can lead to extensive fouling during themembrane filtration step. Thus, a physical separation step can then beapplied to remove the insoluble material from the hydrolyzed oatmixture. Centrifugation, decantation, and/or sieving can be used forthis step to obtain a soluble hydrolyzed oat mixture. Whencentrifugation is used, a pH adjustment step is required before thephysical separation step to avoid protein precipitation. This pHadjustment step is not required when decantation or sieving is used.

Preferably, decantation is used for this step. Decantation can lead toefficient removal of insoluble materials as well as a high oat proteinrecovery yield over the process. In some embodiments, the proteinrecovery rate from decantation can be about 80-90%.

In a preferred embodiment, the process of the invention does notcomprise any additional decantation step after the physical separationstep. Especially, when the physical separation step is performed bydecantation, the process of the invention comprises a single decantationstep. A decanter centrifuge is based on the principle of sedimentationin a liquid medium which is accelerated by a centrifugal force. Thedecanter distinguishes itself from other centrifuges by a continuousremoval of the sediment by an axial screw conveyor. The difference inspeed between the bowl and the conveyor is called the differentialspeed, which makes the solids move to the solids discharge. Thedifferential speed impacts the residence time of the product and thedryness of the final cake that leaves the machine at the solidsdischarge. When compared to other liquid-solid separation techniques,the decanter centrifuge can often run at higher volumes in a continuousdesign. Moreover, the solids that leave the decanter centrifuge oftenhave a lower water content due to the screw that presses the last bit ofwater out of the solids.

The pH of the oat hydrolysate, without adjustment, can be below 7, forexample, about 6.3. If centrifugation is used, the pH value of thehydrolyzed oat mixture is first adjusted to an alkaline pH, such as a pHof about 8, before centrifugation to increase protein solubility andsubsequently to prevent protein precipitation during the centrifugationstep. The final pH can be between 7 and 10, preferably between 8 and 10.Lower pH values can also lead to a significant decrease in the oatprotein recovery yield over the process when centrifugation is used, dueto the low solubility of oat proteins at lower pH values. If decantationor sieving is used for this physical separation step, no pH adjustmentis necessary. In particular, if decantation or sieving is used for thisphysical separation step, the retentate has a pH of 6.0 to 7.0,preferably of 6.2 to 6.6. If the oat raw material comprises oat flakes,the insoluble material can be physically separated from the hydrolyzedoat mixture by sieving.

Insoluble fibers can be separated and obtained from the physicalseparation step and can be used as and/or in a natural fiber product,which can be used in food product. The obtained insoluble fibers cancomprise about 4-10 wt % of oat proteins; about 1-4 wt % of fat; about5-20 wt % of carbohydrates; about 2-3 wt % of sugars, mostly maltose;and about 5-20 wt % of total dietary fibers comprising about 0.1-1 wt %of soluble fibers (beta-glucan). The obtained insoluble fibers can havea TS of about 15-50%.

In one embodiment, the obtained insoluble fibers comprise about 8 wt %of oat proteins; about 2 wt % of fat; about 10 wt % of carbohydrates;about 2-3 wt % of sugars, mostly maltose; and about 10 wt % of totaldietary fibers comprising about 0.5 wt % of soluble fibers(beta-glucan). The obtained insoluble fibers can have a TS of about 30%.

The insoluble fibers can be freeze-dried or spray-dried to produce a dryfiber product. The dried insoluble fibers can comprise about 15-30 wt %of oat proteins; about 3-10 wt % of fat; about 20-40 wt % ofcarbohydrates; about 4-16 wt % of sugars; and about 16-60 wt % of totaldietary fibers comprising about 15-56 wt % of insoluble fibers and about1-4 wt % of soluble fibers. The dried fiber product can have a TS ofabout 90-98%.

In one embodiment, the dried insoluble fibers comprise about 25 wt % ofoat proteins; about 7 wt % of fat; about 30 wt % of carbohydrates; about8 wt % of sugars; and about 32 wt % of total dietary fibers comprisingabout 30 wt % of insoluble fibers and about 2 wt % of soluble fibers.The dried fiber product can have a TS of about 95%.

The soluble hydrolyzed oat mixture obtained from the physical separationstep may have a TS of about 10-25%. For example, the soluble hydrolyzedoat mixture can have a TS of about 10%, 15%, 20%, or 25%. The solublehydrolyzed oat mixture preferably has a TS from about 10% to about 15%,for example, about 10% or about 15%. If the TS of the soluble hydrolyzedoat mixture is above about 15%, the soluble hydrolyzed oat mixture canbe diluted to have a more preferable TS for the subsequent membranefiltration step.

The membrane filtration step can then be applied to the solublehydrolyzed oat mixture to obtain a retentate and a permeate. Membranefiltration is a pressure driven process in which the feed solution, thesolution to be concentrated or fractionated, is forced through themembrane. Two fractions are obtained by this process: a retentate, whichcorresponds to the retained liquid; and a permeate, which corresponds tothe liquid passing through the membrane.

This membrane filtration step allows the concentration of largemolecules, e.g., proteins and remaining large carbohydrates, which areretained in the retentate, and the removal of small molecules, e.g.,hydrolyzed carbohydrates, that pass through the membrane and are thencollected in the permeate.

The membranes used in this step preferably have large molecular weightcut-offs (MWCO)/pore sizes to ensure a high protein content in theretentate and permeate flux.

The use of lower MWCOs can led to excessive fouling during the membranefiltration process and subsequently to a significant decrease in the oatprotein content in the final retentate. The MWCOs of the membranes usedcan be 100 kDa or greater, for example, between about 100 kDa and about0.2 μm, preferably greater than or equal to 500 kDa.

Flat sheets or spiral wound membranes can be used in this step.Different types of membrane materials can be used. For proteinconcentration applications, a hydrophilic and non-protein bindingmaterial is usually preferable. The membrane material used in thepresent process can be a hydrophilic, hydrophobic, and/or an inorganicmaterial. In one embodiment, the membrane material is preferablyceramic. An adapted membrane material, such as ceramic, cansignificantly increase the protein content in the retentate and permeateflux.

The membrane filtration step can be carried out at a temperature greaterthan 50° C., preferably from about 50° C. to about 60° C. Temperatureslower than 10° C. may lead to excessive fouling due to high viscosity ofthe hydrolyzed oat mixture during the membrane filtration step.Temperatures between 10 and 50° C. may cause microbiological growth.Using higher temperatures, p.e. 60° C., can significantly increase theprotein content in the retentate and permeate flux and are preferred incase the membrane material is not thermo-sensitive.

Different types of membrane filtration, such as microfiltration andultrafiltration, can be used. Each membrane type has pores withdifferent sizes.

In some embodiments, ultrafiltration can be used. “Ultrafiltration” is amembrane filtration technique using hydrostatic pressure to force aliquid through a semi-permeable membrane. Suspended solids and highmolecular weight solutes are retained in ultrafiltration, while waterand low molecular weight solutes cross the membrane. Ultrafiltration isused in industry and research to purify and concentrate solutionscontaining large molecular weight molecules (10³-10⁶ Da).Ultrafiltration allows an efficient and, at the same time, gentleseparation of large molecular weight compounds. Any common type ofultrafiltration membrane may be used in the ultrafiltration, andsuitable ultrafilters are commercially available, for example fromMillipore Corp. and Desal Systems. Techniques by which ultrafiltrationmay be performed include flat, spiral, and hollow fiber techniques, forexample. The ultrafiltration may be performed in various modes, such asdead-end, crossflow and back-flush operating modes. The presentdisclosure is not limited to a specific embodiment of theultrafiltration membrane, the ultrafiltration technique or theultrafiltration mode.

In some embodiments, microfiltration can be used. “Microfiltration” isfiltration that uses a membrane having a pore size range from 0.1 to 10μm and for which pressurization is optional. The microfiltration can usemembranes that are hollow fibers, a flat sheet, tubular, spiral wound,hollow fine fibers or track etched, for example. The present disclosureis not limited to a specific embodiment of the microfilter.

In a preferred embodiment, the process of the invention does notcomprise any step of sterilization, i.e. a step of heat treatment attemperatures above 100° C., before the membrane filtration step. Indeed,sterilization would lead to the aggregation/denaturation of the oatproteins which would negatively affect the functionality (e.g.solubility) of oat proteins, especially for RTD beverage applications.

A retentate can be obtained after the membrane filtration step. Theretentate contains highly functional oat proteins and can be used inand/or as an oat protein concentrate. In an embodiment, the oat proteinconcentrate can comprise about 5-10 wt % of oat proteins; about 2-7 wt %of fat; about 5-20 wt %, for example, about 10 wt % of carbohydrates;about 2-4 wt % of sugars, mostly maltose; and about 1-2 wt % of totaldietary fibers comprising (i) about 1-1.5 wt % of insoluble fibers and(ii) up to about 0.5 wt % of soluble fibers comprising β-glucans. Theoat protein concentrate can have a TS of about 20-40%, for example,about 25-40% or about 20-30%. In a preferred embodiment, in the contextof the invention, the oat protein concentrate is a retentate obtained bythe process according to the invention. In a more preferred embodiment,the retentate can comprise about 5-10 wt % of oat proteins; about 2-7 wt% of fat; about 5-20 wt %, for example, about 10 wt % of carbohydrates;about 2-4 wt % of sugars, mostly maltose; and about 1-2 wt % of totaldietary fibers comprising (i) about 1-1.5 wt % of insoluble fibers and(ii) up to about 0.5 wt % of soluble fibers comprising β-glucans. Theretentate can have a TS of about 20-40%, for example, about 25-40% orabout 20-30%.

Preferably, the oat proteins of the retentate or the oat proteinconcentrate are intact. Oat proteins which are intact have goodfunctionality, such as improved solubility compared toaggregated/denatured oat proteins.

In a preferred embodiment, the retentate has a pH of 6.0 to 7.0, morepreferably of 6.3 to 6.6. These pH ranges of the retentate contribute topreserve the functionality of oat proteins. In particular, if the pH ofthe retentate is below these ranges, it may lead to the aggregation ofthe proteins which may negatively impact the functionality (e.g.solubility) of oat proteins.

The oat protein concentrate contains highly functional oat proteins withhigh stability, solubility, gelation, emulsification, and foamingproperties. The oat proteins in the oat protein concentrate can maintaintheir best performance due to the mild processing by membranefiltration. The oat protein concentrate has a high oat protein content,which is concentrated by membrane filtration. The oat proteinconcentrate also has a controlled sugar generation and/or sugarreduction due to the hydrolysis of carbohydrates and partial removal ofthe hydrolyzed carbohydrates (sugars) by membrane filtration,respectively. Further, the protein/sugar ratio of the oat proteinconcentrate can be modulated by process control and/or combination ofdifferent streams during/by the present process.

As shown in FIG. 1 , compared to a commercial oat protein concentrate,the protein in the oat protein concentrate obtained by the presentprocess has a greater solubility of about 20% or greater at a pH>=4. Forexample, at a pH >=5, the oat protein concentrate obtained by thepresent process has a protein solubility of about 30% or greater; and ata pH >=6, the oat protein concentrate obtained by the present processhas a protein solubility of about 40% or greater. Notably, at a pH >=7,the oat protein concentrate obtained from the present process has aprotein solubility of about 80%, which is much higher than that of thecommercial oat protein concentrate, which is only up to about 5% at a pHof 4-11.

As shown in FIG. 2 , compared to the commercial oat protein concentrate,the protein in the oat protein concentrate obtained by the presentprocess has greater foaming properties. During the whole time measured,the oat protein concentrate obtained from the present process has afoaming volume of at least 4 times (about 100 mL or greater) of that ofthe commercial oat protein concentrate (up to 25 mL).

Additional ingredients can be added to the retentate or the oat proteinconcentrate to produce oat-based ready-to drink (RTD) beverages. Forexample, at least one of sugar, preferably sucrose; oil, preferablysunflower oil; buffer salts and sources of calcium, preferablydipotassium phosphate and tricalcium phosphate; or flavor enhancers,preferably sodium chloride, can be added to the retentate. Sodiumchloride is a flavor enhancer which contributes to the reduction ofoff-notes in the oat-based products (e.g. retentate, oat proteinconcentrate, oat-based RTD beverage), including bitterness andastringency. The buffer salts may also be disodium phosphate. Thesources of calcium may also be calcium carbonate.

One or more vitamins and/or minerals can also be added to the retentateto produce the oat-based RTD beverages. Examples of minerals, vitaminsand other micronutrients optionally present in the oat-based RTDbeverages include vitamin A, vitamin B1, vitamin B2, vitamin B6, vitaminB12, vitamin E, vitamin K, vitamin C, vitamin D, folic acid, inositol,niacin, biotin, pantothenic acid, choline, calcium, phosphorous, iodine,iron, magnesium, copper, zinc, manganese, chloride, potassium, sodium,selenium, chromium, molybdenum, taurine, and L-carnitine.

Optionally, a permeate, rich in carbohydrates and/or hydrolytes thereof,can be obtained from the membrane filtration step. The permeate can besteamed and/or evaporated to obtain an evaporated permeate, which can beused in and/or as a side product of an oat syrup. The oat syrup can alsobe added to the retentate or the oat protein concentrate as analternative source of sugar.

In one embodiment, the oat syrup can comprise up to about 1 wt % of oatproteins; up to about 0.1 wt % of fat; about 40-50 wt % ofcarbohydrates; about 20-30 wt % of sugars, mostly maltose; and up toabout 0.5 wt % of fibers. The oat syrup can have a TS of about 65-80%.

A heat treatment, for example, an ultra-high temperature (UHT)treatment, including up or downstream homogenization, can be applied tothe mixture of the retentate or the oat protein concentrate and theadditional ingredient(s). The heat-treated mixture can then be asepticpackaged. The oat-based RTD beverage can be used in and/or as a dairyalternative product.

In one embodiment, the oat-based RTD beverage can comprise at leastabout 3 wt %, preferably about 3 to 5 wt % of oat proteins and/or 3-5 goat proteins/100 ml of the oat RTD; about 3-5 g sugars/100 ml of the oatRTD; and about 1.5-3 g fat/100 ml of the oat RTD. The oat RTD can have aviscosity of 15-40 mPa·s (25° C., 100 s⁻¹). Preferably, the oat proteinsof the oat-based RTD beverage are intact. Oat proteins which are intacthave good functionality, especially for RTD beverage applications, suchas improved solubility compared to aggregated/denatured oat proteins.The oat-based RTD beverage contains highly functional oat proteins withhigh stability, solubility, gelation, emulsification, and foamingproperties. The oat proteins in the oat-based RTD beverage can maintaintheir best performance due to the mild processing by membranefiltration. The oat RTD has great sensory and nutritional performance.The oat-based RTD beverage has smooth taste and mouthfeel due to thehigh viscosity promoted by intact oat proteins and/or the right enzymechoice and/or salt addition. The oat-based RTD beverage has a high oatprotein content, which is concentrated by membrane filtration. Theoat-based RTD beverage also has a controlled sugar generation and/orsugar reduction due to the hydrolysis of carbohydrates and partialremoval of the hydrolyzed carbohydrates (sugars) by membrane filtration,respectively. Further, the protein/sugar ratio of the oat-based RTDbeverage can be modulated by process control and/or combination ofdifferent streams during/by the process.

In a preferred embodiment, the oat-based RTD beverage has a pH of 7 to7.7, preferably a pH of 7.3 to 7.7, more preferably of 7.5. Especially,the pH of the beverage may be regulated by using a buffer salt, such asdipotassium phosphate or disodium phosphate. At this range of pH, theoat-based RTD beverage does not exhibit physical instability phenomenonover the shelf-life which may negatively impact the visual aspect andthe organoleptic profile of the oat-based RTD beverage. For example, itdoes not exhibit protein aggregation and viscosity increase. Inaddition, at this range of pH, the off-notes, including astringency, ofoat-based RTD beverage are reduced.

EXAMPLES Example 1: Process

In an example process, an enzyme or an enzyme blend (0.2% weight of oatflour) was mixed with water, and oat flour was gradually added to reacha TS of 15%. The mixture was heated and kept at 60° C. for 1 h. Themixture was homogenized (200/50 bars, and preferably at 60° C.), heatedto 90° C., hold at 90° C. for 10 min to inactivate the enzymes andcooled to 60° C. Then, the oat slurry was passed through a decanter(6000 rpm drum, 10 rpm screw, 500 L/h). The obtained heavy phase wasoven dried at 105° C. for about 2-3 h and subsequently dry milled andsieved (mesh 1 mm). Membrane filtration was applied to the obtainedlight phase (i) with a spiral membrane made from regenerated cellulose(RC) with a 500 kDa MWCO and a membrane area of 11.4 m², at 50° C., witha flow of 3000-3800 L/h and a transmembrane pressure of about 1.2 bar;and (ii) alternatively, with a ceramic membrane with a 0.14 μm MWCO anda membrane area of 7.6 m², at 60° C., with a flow of 1900-3300 L/h and atransmembrane pressure of about 1.8 bar. The permeate obtained from themembrane filtration step was concentrated in a two-stage evaporator. Theobtained retentate was mixed with other ingredients (e.g., water, sugar,sunflower oil, tricalcium phosphate, dipotassium phosphate) to producethe RTD product, followed by indirect UHT treatment and aseptic fillingin bottles.

Example 2: Enzymatic Hydrolysis

A Rapid Visco Analyzer (RVA) was used to simulate the hydrolysis andinactivation steps. Commercially available enzymes are used for thetests. FIG. 3 and FIG. 4 are the RVA profiles for the different enzymestested. FIG. 3 shows that the α-amylase Maxamyl® without any otherenzyme results in an oat slurry with the highest viscosity. FIG. 4 showsthat Maxamyl® in combination with the amyloglucosidase (AMG) resulted inthe highest viscosity compared to all the other samples in FIG. 4 . Thedifference between the 2 α-amylases tested, BAN™ 480L and Maxamyl®, isthe β-glucanase side-activity of BAN™ 480L. The cleavage of β-glucanshas a big impact on the viscosity. This is also shown by the combinationof Maxamyl® and the β-glucanase Viscozyme®, which has a similarviscosity profile as BAN™ 480L.

The combination of two α-amylases, BAN™ 480L and Termamyl®, was alsoinvestigated. Table 1 and FIG. 5 show the results.

TABLE 1 Results from trials carried out with different TS values whereBAN ™ 480L was used either alone or in combination with Termamyl ®.Protein on TS in TS (%) TS (%) the TS of Initial after of the retentatepermeate TS (%) decantation retentate (%) (%) BAN ™ 15 14.5 27.9 24.311.0 480L BAN ™ 15 14.3 32.1 33.2 11.8 480L + Termamyl ® BAN ™ 25 24.333.4 23.8 18.3 480L BAN ™ 25 24.0 36.4 28.5 18.8 480L + Termamyl ®

These results indicate that the combination of BAN™ 480L with Termamyl®results in higher permeate flux (FIG. 5 ) and subsequently a higherprotein content on TS in the retentate (Table 1).

Example 3: Initial Total Solids (TS)

The initial TS of the oat slurry corresponds to the ratio of oat flourto water at the beginning of the process. Table 2 summarizes the resultsof trials with different initial TS values, and FIG. 6 shows thepermeate flux of these trials during the membrane filtration step.

TABLE 2 Results from trials carried out with a decanter and differentinitial TS values. After After membrane filtration mechanical Protein onseparation step TS in the (decantation) retentate TS of Initial TS (%)TS (%) TS (%) (%) permeate (%) 15 13.7 28.7 28.0 9.5 20 17.8 31.0 25.513.1 25 22.5 31.0 22.8 16.5

During membrane filtration, the permeate flux of samples with a higherTS was lower as shown in FIG. 6 , as viscosity, concentrationpolarization and fouling are higher at a higher TS.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

Example 4: RTD Beverage

The retentate obtained via membrane filtration in Example 1 was used toproduce an oat-based RTD beverage containing 3% oat protein. Theretentate was mixed with other ingredients (described in Table 3 below)for 30 minutes at ambient temperature. The mixture was then UHT treatedat 145° C. for 6 seconds, homogenized at 200/50 bars at 78° C., cooleddown to 20° C. and aseptic filled in plastic bottles. The oat-based RTDbeverage has a pH of 7.5.

TABLE 3 Ingredients % in recipe Retentate (from Example 1) 60.0 BrownSugar 3.00 Tricalcium Phosphate 0.35 Dipotassium Phosphate 0.80 SodiumChloride 0.06

1. A process of producing an oat-based product, the process comprising:providing an oat mixture; hydrolyzing the oat mixture with an enzyme ora combination of enzymes; physically separating an insoluble materialfrom the hydrolyzed oat mixture by decantation and/or sieving to form asoluble hydrolyzed oat mixture; and applying membrane filtration,preferably at a temperature from 50° C. to 60° C., to the solublehydrolyzed oat mixture using a membrane having molecular weight cut-offs(MWCO) greater than 100 kDa.
 2. The process of claim 1, wherein the oatmixture comprises an oat raw material selected from the group consistingof oat flour, defatted oat flour, oat flakes, and mixtures thereof. 3.The process of claim 1, wherein the enzyme(s) comprise amylase.
 4. Theprocess of claim 1, wherein a total amount of the enzyme used forhydrolyzing the oat mixture is from 0.05 wt % to 0.3 wt % of the oat rawmaterial.
 5. The process of claim 1 further comprising inactivating theenzyme at 90° C. to 95° C. for 10-15 minutes and cooling the hydrolyzedoat mixture to 20-60° C.
 6. The process of claim 1, wherein the membranecomprises a ceramic membrane.
 7. An oat protein concentrate comprising:5-10 wt % of oat proteins; 2-7 wt % of fat; 5-20 wt % of carbohydrates;2-4 wt % of sugars, mostly maltose; and 1-2 wt % of total dietary fiberscomprising (i) 1-1.5 wt % of insoluble fibers and (ii) up to 0.5 wt % ofsoluble fibers comprising β-glucans, and wherein the oat proteinconcentrate has a TS of 20-30%.
 8. The oat protein concentrate of claim6, wherein the oat proteins has a solubility of 20% at pH 4 and of83-86% from pH 7 to pH
 11. 9. An oat-based ready-to drink (RTD) beveragecomprising providing an oat mixture; hydrolyzing the oat mixture with anenzyme or a combination of enzymes; physically separating an insolublematerial from the hydrolyzed oat mixture by decantation and/or sievingto form a soluble hydrolyzed oat mixture; and applying membranefiltration, preferably at a temperature from 50° C. to 60° C., to thesoluble hydrolyzed oat mixture using a membrane having molecular weightcut-offs (MWCO) greater than 100 kDa concentrate; and at least one ofsugar.
 10. The oat RTD beverage of claim 9 comprising: at least 3 wt %,preferably 3 to 5 wt % of oat proteins and/or 3-5 g oat proteins/100 mlof the oat RTD beverage; 3-5 g sugars/100 ml of the oat RTD beverage;and 1.5-3 g fat/100 ml of the oat RTD beverage, wherein the oat RTDbeverage has a viscosity of 15-40 mPa·s (100 s⁻¹). 11-12. (canceled)